Create Account Settings Controller/Page

- Create account settings controller/view/route
- Move account deletion form to account settings page
initial commit of 2fa settings section
first pass at mobile confirmation refactor

Using user.mobile_number for SMS 2-factor now, rather than profile phone number. Also introduced user.uncofirmed_mobile_number to prevent users from changing mobile number without confirmation.
SMS 2FA should not erase confirmed mobile number
User should redirect back to account settings after setting up 2FA

When 2FA enrollment/mobile confirmation is part of the first time experience, user should be sent to a welcome page. When 2FA enrollment is triggered directly from account settings, user should just get redirected back.
remove old mobile_recoveries table
remove roles_helper.rb

move the roles helper functions into application controller
Clean up account settings controller/view

- remove instance variables
- don't seperate public/private apps in warning
Update privacy policy and privacy act notice to reflect SORN routine uses

The privacy act and privacy policy need to include disclosures from
the SORN's routine uses in order to comprehensively describe when
and where your information may be shared.
Clean up mobile number error messaage
More routine use adjustments and link to GSA Privacy Program
Report Twilio phone number validation errors
Remove extra )
Generate HTML/MD for updated privacy docs
Merge pull request #456 from 18F/hotfix/privacy-policy

Update privacy policy and privacy act notice to reflect SORN routine uses
Minor privacy change to be more accurate

As requested by our friends at OIRA
Merge pull request #458 from 18F/hotfix/profile-privacy-stmt

Minor privacy change to be more accurate
audit profile and application updates
Merge pull request #461 from 18F/feature/audit_some_updates

audit profile and application updates
cleanup